Secret Character
Complete the game once with any character. The next time you create a new file, a new Black Mage character will be selectable.

Multiply money
First, have over 100,000 gold in your bank and inventory combined. Next, put any amount of money into your inventory. Finally, grab the money in the bank and drop it on the money in your inventory. Make sure the total will exceed 100,000. When you do this, the bag that had the lowest amount of money will be duplicated. A new bag of money will appear with that amount in it, the bag that was originally in your inventory will have 100,000 gold in it, and the money from your bank will still be in your bank. This will not work if there is a money bag in your first two item slots. Also, whatever is in those slots will be replaced with the money.